Acoustic Emission Signals and Wear Phenomena on Severe-Mild Wear Transition

Abstract

The relationship between acoustic emission (AE) signals and wear phenomena in severe-mild wear transition is discussed on the basis of the results of observations of wear particles and worn surfaces of steel. Each wear mode, severe wear or mild wear, is reproduced for a different sliding velocity. The influence of relative humidity on mild wear is examined. We found a reduction in the true area of contact and the size of wear particles decreases the AE signal level in severe-mild wear transition. In the mild wear mode, an increase in the number of transfer particles lying between the sliding surfaces decreases the AE signal level. Further, a linear relationship is observed between the AE mean value and the specific wear rate, regardless of the wear mode. This is because the AE signals generated by the formation and removal of transfer particles mainly originate under conditions of repeated dry rubbing.

Acoustic Emission in Elementary Processes of Friction and Wear: In-Situ Observation of Friction Surface and AE Signals

“…Because back transfer is not a direct fracture from inside of a material unlike the generation (transfer) of wear elements, the amplitude of burst-type AE signals tends to be smaller than that in the generation of wear elements. It appears that this is caused by the release of the elastic stress energy stored in a transfer particle (11,12) .…”

“…In particular, under dry repeated rubbing, the formation and the behavior (collision and removal) of wear particles at the frictional interface affect AE signals greatly (11,12) . Thus, the phenomena under repeated rubbing become a many-body problem that includes friction surfaces and wear particles between them (strictly speaking, atmospheric substances must also be included).…”

Real-time fretting loop regime transition identification using acoustic emissions

“…Three distinct stages were identified by the rate of recorded hits as initiation, plastic response at the crack tip followed by shearing between micro-voids. Wear processes have also been investigated using AE 32,33 . The root mean square voltage of acoustic hits has been found to increase with increased specific wear rate 32 .…”

Using acoustic emission to characterize friction and wear in dry sliding steel contacts

“…The integrated AE RMS can be related to frictional work and wear under different sliding speeds [18] and loads [21] and can detect the sliding speed threshold for accelerated wear [18]. The integrated AE RMS [22,23] may also have a direct correlation with the wear volume and wear rate [24].In the frequency domain, AE parameters such as energy and median frequency (MDF) can be used, with the former being correlated to CoF [25,26] and wear volume [27] and the latter being correlated to CoF [26,28] and frictional work [29]. The amplitude of individual AE frequency components can also be excited by specific wear mechanisms, which can be determined based on power spectral density (PSD) and auto-covariance techniques [30].…”

“…The integrated AE RMS can be related to frictional work and wear under different sliding speeds [18] and loads [21] and can detect the sliding speed threshold for accelerated wear [18]. The integrated AE RMS [22,23] may also have a direct correlation with the wear volume and wear rate [24].…”